Dear All,

During the course of the last two weeks or so, ILAQH has received more than a thousand e-mails in relation to the study on printer emissions, and the e-mails continue to come. I am extremely grateful for your comments, suggestions, for sharing with me your experiences related to the topic and also for positive comments about our study. I would dearly like to respond to each of you individually, but this is not possible, as there are not enough hours in the day to do so. Therefore, in this e-mail addressed to all of you, I will try to respond to the most commonly asked questions and queries.

There is not. In our study we investigated all of the printers which were in the large office building, but only those which were there. Also, it is important to remember that the study of the building was initially based on a different study, where we investigated the efficiency of filtration and ventilation system in protecting the indoor environment from vehicle emissions on a nearby busy road. Since, at times, concentrations inside were much higher than outside, we had to find a reason for this, which turned out to be the printers.

Can it be assumed that emissions from some other models, not investigated in the study, are similar to some of the models covered by the study?

It cannot. The emissions are very model-specific and therefore, until more data on particle formation in the printing process is available, we cannot make such assumptions.

Some of you asked very specific questions in relation to specific distances. In simplistic terms, exposure is defined as the concentration in the microenvironment(s) where the exposure occurs, multiplied by the exposure duration. Concentration on the other hand, depends of the source strength over time but also on the dispersion properties, which in turn depend on ventilation and flow characteristics. Therefore, without knowing all these factors (and a few more), it is not possible to calculate exposure. In addition, since such calculations are complex and time consuming, I would not be able to conduct them for all those who expressed interest in knowing the figures.

In our study we did not investigate the chemistry of the particles (only their physical properties, including concentration and size distribution), therefore I would not like to speculate on this.

We believe that, at the time when the study was conducted, the cartridges on the Australia market were mostly the original ones, while now it is becoming more common to use refilled cartridges. We did not include information about the cartridges for the printers investigated in the office, because we did not have this information available. However, the printers investigated in the laboratory (chamber part of the study) original cartridges were used. We expect that different cartridges (original, refilled by the original manufacturer, refilled by the others, as well as the number of refillings) may have different particle emission properties. This would certainly be a topic for an extension of this study.

Their behavior would be similar to the behavior of other particles of a similar size range. Some of them will be removed from the indoor air by ventilation and some will be deposited onto indoor surfaces (not only the floor). Re-suspension from the surfaces is not a likely process for particles in such a small size range. Since we are not sure what the chemical composition of the particles is, we do not know what changes may occur to their chemistry with time.

In what sense is the exposure (and health effects) from inhalation of these printer emitted particles similar to those from inhalation of cigarette smoke?

The similarity is in the particles size range and concentrations. Particles emitted by printers, likewise with those from cigarette smoke, are in the ultrafine size range (< 0.1 micrometer), and therefore can penetrate to the deep regions of the respiratory track. Increasing numbers of toxicological studies point to the health risk due to the inhalation of ultrafine particles. The concentration of the particles from printer operation can reach similar levels as concentration of second hand cigarette smoke.

This is, however, where the comparison ends. While the chemistry of particles was not investigated in our study, it is expected that cigarette smoke and printer emitted particles will have a different chemical composition, as the formation mechanisms (combustion versus printer operation) are different.

It all depends how you use them and what the ventilation is like in your home. If you print a page or so from time to time, in a reasonably ventilated houses (some windows opened), I would not imagine that particle concentration would reach levels of concern. If however, we print document after a document for a long period of time, in an enclosed room, then the particle concentrations could reach levels of concern.

In general, an increase in ventilation where the printers are and/or moving printers to well ventilated areas away from people would help reduce exposure. Also, avoid having printers operating frequently in the areas where people sit and try to buy low emitting printers (while at this point there is still very little information available on this – I do not know about any other documents apart from our paper that list printer types – I hope that this situation will change very soon).

I would not like to recommend any specific method or equipment. On the one hand, there is no standard for testing printer emissions in existence, and on the other hand, this kind of investigation requires some level of expertise in the area, even when using hand held equipment (without expert interpretation, the results would not be meaningful).

There are many more questions, which need to be addressed in order to fully understand the characteristics of the particles emitted by printers and the factors effecting the emissions. Such information is of importance to printer manufactures as it would help them to develop no emitting printers, and for all of us to avoid exposures. Our intention is to conduct more studies in this area.

Once again, I thank you all for your comments, which we will take into consideration in the continuation of our studies on printer emissions.

Lidia Morawska, PhD
Professor, School of Physical and Chemical Sciences
Director, International Laboratory for Air Quality and Health
Queensland University of Technology
2 George Street
Brisbane, Q 4001 Australia
See International Laboratory for Air Quality and Health: www.ilaqh.qut.edu.au